To achieve the main objective, it is planned to compare the ratio between Uf graft site and the opposite healthy site between two groups: skin + matrix graft , or skin graft only. Thus, the Wilcoxon test for independent samples will be used to settle bilateral formulation between the null hypothesis ( there is no difference between the two groups ) and the alternative hypothesis ( there is a difference between the two groups ) . In determining the overall risk of first species to 5% and the power of this test to detect the 90% expected under the alternative hypothesis difference should be the main criterion for evaluating at least 59 patients in each group so 118 patients total.